1. Field of the Invention
This invention relates to devices for testing electronic channels more particularly to devices for testing digital electronic channels.
2. Previous Art
For as long as there have been digital electronic devices, there has been a need for devices to test them. It is of particular importance in the area of digital electronic devices because the functions performed by these devices are incredibly specific and the digital device must perform with an extremely high degree of accuracy. For the purposes of this patent application, it will be assumed that all digital electronic devices have at least one digital electronic channel and it is in actual point of fact that the channel is what is tested by the testing equipment.
Traditionally, a digital channel is tested by transmitting a known data sequence through the digital channel and then comparing the known sequence with the data after it goes through the channel for errors. Representative of this type of testing device are the testing devices made by Tau-tron, Hewlett-Packard and Anritsu Bit Error Test Sets.
More advanced devices such as de Couasnon, U.S. Pat. No. 4,380,068 (the entire disclosure of which is specifically incorporated herein by reference), and Ampex's Bert Rack have been developed for internal company usage for specific applications and are not suitable for general testing. All these devices create a pattern which is then fed through the device under test and then the device under test is connected to a detector member which compares the known pattern to the pattern after it has been through the device under test. The detector member counts any deviation from the expected result as an error.
As with de Couasnon, U.S. Pat. No. 4,380,068, prior devices compare each bit in a serial fashion. For modern digital channels, this requires the testing device to perform at a very high rate of speed to enable the data to be analyzed. While devices such as de Couasnon, U.S. Pat. No. 4,380,068, are highly useful for showing the total number of error in the data stream (bit error rate also referred to as BER), such information does not give error location or allow grouping of error data for graphical analysis. Thus, the diagnosis of the machine is left in question. Additionally, the expense of adapting a device such as de Couasnon, U.S. Pat. No. 4,380,068, which processes data at modern serial bit rates, makes such a device uneconomical and impractical for many applications.
Prior devices such as the Tau-tron BERTS-350C and BERTS-650, the HP 3784A, 3788A, 3780A and 3764A, Anritsu ME643A and M448A and M448B, and Wandel & Goltermann PF3 and PF4 give test results informing the user the total error rate of their machines. This single result does not assist the user in diagnosing the cause of the errors. The BER would be the same whether the errors were spaced apart evenly or occurred in blocks. However, a machine malfunction causes errors to occur in blocks. Using currently existing testing there is no difference between block errors and those which are evenly spaced apart. Thus, it would be a great diagnostic advantage to have more detailed information to discern the difference between such error types.
Additionally, prior devices do not provide users with graphical analysis of the errors and can not because they lack a high speed interface to a computer and a graphic display.
Many of the testing devices such the Tau-tron BERTS-350C and BERTS-650, the HP 3784A, 3788A, 3780A and 3764A, Anritsu ME643A and M448A and M448B, and Wandel & Goltermann PF3 and PF4 are quite large and expensive. Thus, the above devices lack the ability to be easily transported.
What is needed is a device which performs accurately and reliably and may be used with a wide variety of different digital electronic devices. Additionally, the new device should be able to work effectively and deliver graphical analysis to the user so that the user can instantaneously determine error patterns within his tested device. Additionally, the new device should be adapted such that it can do all the above with the power and size of a personal computer based on standard computer parts, such as Intel's 80386 chip so as to minimize costs and allow for portability. Finally, the ideal device should provide compatibility for error information to be interchanged with other computers for even further user specific analysis.